Nickel base alloy



Nov. 19,1968 SCH L ETAL 3,411,898

NICKEL BASE ALLOY Filed March 25, 1966 COMPARATIVE LARSON MILLER CURVES 10 HRS.

l l 1300 7 35 40 s 6 66 I00 HRS. I

7 HIS INVENTION ALLOY A so ALLOY a L 7o m 40 v i &2

as '39 40 4| 42 4a 44 45 T (20mg t) lo' mvzm'ons DAVID W SCHULTZ PETER 1.. LANSING GLENN 4 rn/rzuw M/m4.

ATTORNEY United States Patent 3,411,898 NICKEL BASE ALLOY David W. Schulz, Peter L. Lansing, and Glenn A. Fritzlen, Kolromo, Ind., assiguors to Union Carbide Corporation, a corporation of New York Filed Mar. 25, 1966, Ser. No. 537,351 2 Claims. (Cl. 75-171) The present invention relates to nickel base alloys. More particularly the present invention relates to a nickel base alloy in wrought form characterized by improved welding properties and superior hardness, strength, and endurance properties at high temperatures.

A substantial advance in the field of nickel-base alloys over about the past decade has been the development of precipitation hardened alloys wherein the precipitate is Ni (A1,Ti), gamma prime. The addition of particular amounts of titanium and aluminum to nickel base alloys causes the development of the aforementioned precipitate in a dispersion throughout the solid solution matrix of the alloy. Such alloys in cast form have been found to be especially useful under severe operating conditions when used as blades and vanes in gas turbine engines.

However, previously known precipitation hardened nickel-base alloys have been difiicult to fabricate and, when in wrought form, are subject to serious limitations especially as regards tensile strength, durability and welding prop erties.

It is therefore an object of the present invention to provide a nickel base alloy which can be readily fabricated.

It is another object of the present invention to provide a nickel base alloy in wrought form characterized by improved hardness, strength, endurance and welding properties.

Other objects will be apparent from the following description and claims taken in conjunction with the drawing which shows a graph comparatively illustrating improved properties of the alloy of the present invention.

An alloy in accordance with the present invention is a precipitation-hardened nickel alloy containing Ni (Al,Ti) precipitate consisting essentially of by weight percent:

Broad Range Preferred Hpoatoqp opgn v c 1 Balance.

In the present invention the rather narrow limits for the constituent materials are critical in order to obtain the improved properties hereinafter noted. For example, 14 to 17% chromium is required to provide an industrially desirable balance between ductility, strength and corrosion resistance. Chromium contents over 17%, for example tend to embrittle the alloy whereas Cr contents less than 14% tend to cause reduced strength and lessened corrosion resistance.

In the present invention it has been found that both tungsten and molybdenum must be present with the tungsten in the range of 1 to 3% and the molybdenum must be present in the range of 6 to 9%. Vanadium must be present in the alloy in the range of 0.65 to 1.35% as a carbide former and to suitably limit grain size in the alloy. Vanadium, when present in the range of 0.65 to 1.35% serves as a grain refinement agent thus enhancing ductility, strength and stability.

Titanium and aluminum must also be present in the ranges of 2.5 to 3.5% and 1.5 to 2.5% respectively in order to form the gamma prime precipitate, Ni (A1,Ti).

With the foregoing elements present in the indicated proportions a complex matrix is formed which is very stable at elevated temperatures and has excellent strength and endurance properties.

In addition to the above mentioned constituents, boron must be present in the alloy in the range of 0.003 to 0.012% in order to improve the creep properties of the alloy as shown in Table V and also to improve the ductility of the alloy in the 13001350 F. range. Boron contents above 0.012% tend to depress the melting point of the alloy and embrittle it at room temperaure and below.

In the present invention iron can be adventitiously present in amounts up to 4.5% maximum and preferably is not more than 3.5%. At iron contents above 4.5% restraint-weld tests have shown that iron causes a loss of strength in the alloy.

Cobalt may also be present adventitiously up to 2% and is preferably less than 1% since the presence of cobalt tends to detrimentally affect the alloy in almost all of the desired properties. Best results are obtained without cobalt and it is also important that the alloy be essentially free of manganese zirconium, columbium and tantalum.

With regard to silicon, it has been found that this element must be limited to 0.12% maximum in order to obtain improved stress rupture properties as shown in Table I.

The composition of the alloys noted in Table I, is shown together with other pertinent alloys in Table II, and it can be seen that a very small difierence in silicon content results in a very substantial difference in properties. That is to say, with reference to Table I, it can be seen that alloys 82 and 543 of this invention containing 0.06 and 0.03% silicon respectively, have much better properties than alloys 550 and 551 which contain 0.22 and 0.21% silicon and are outside the scope of the present invention.

The alloys tested and noted in Table I were in the form of 0.063" sheet and were prepared by vacuum induction melting, forging at 2100" F. to about 0.75 inch plate and hot rolling at 2100 F. to 0.063 inch sheet.

TABLE I Stress, Temp, Life, Silicon Alloy P.s.i. F. Hours Content,

Percent Alloy 550 75, 000 1, 350 +2. 8 0. 22 D 40, 000 1, 500 10. (i 0. 22

r TABLE IL-CHEMICAL ANALYSES'FOR EXPERIMENTAL ALLOYS Composition in Weight Percent A110 No.

y Cr W Fe Si Co Ni Mn V B Mo A1 T 2. 10 3. 35 07 01 Bal. 04 86 006 6.98 2.02 3. 06

2.15 3.87 .20 .08 1 08 Bal. .05 .92 021 6.60 2.11 3.02

1. 75 3. 50 04 04 Bal. 01 1. 09 006 7. 23 1. 28 2. 66

2.08 3. 93 08 04 02 Bal. 01 97 006 6. 81 1. 47 3. 20

1.58 3.50 .03 .08 Bel. 1.02 .003 7.36 2.00 2.28

2.19 3. 50 .08 .02 2a Bal. .01 .91 009 7. 23 1.53 2.57

1.89 5.45 .11 .06 12 Bal. .01 .85 009 6.98 2.04 2.98

1. 90 5. 45 12 12 Bal. .01 85 010 7. 10 2. 22 3.10

2. 02 3. 95 .06 .22 16 Bal. 02 77 008 6.92 2. 07 3.28

2.13 3.23 .10 .21 1 10 Bal. .01 .77 0 6.98 1.97 3.28

0.5 1 0.08 0.3 11 Bal. 0 005 10 1.5 3.2

0.5 1 0.1 0.2 13 Bal 4 1.2 2.5

Alloy of this invention,. .One of the problems associated with previously known tion melting, forging at 2100 F. to about 0.75 inch and Commercial alloys of the gamma prime strengthened type hot rolling at 2100 F. to 0.063 inch.

relates to failure of welded components in the aged con- TABLE IV AVERAGE TENSILE PROPERTIES OF TH dition. With these alloys characteristic cracks 1n the heat- ALLOY OF THIS INVENTION afiFected zone'and crack propagation into the parent metal Ultimate Yield Strength Elongation are believed to result from low duct11ity of the material Temperature. ig g g Percent in tension.'Restraint-weld tests (which involves Welding a disc of the metal under test inside a doughnut section 191,000 143,000

176, 000 134, 000 23. 0 of the same material, using the test material for the 175,000 132,500 weld, and heating to 1400 F. over 1 /2 hours, aging for i2 1 3 2 888 3-8 16 hours and air cooling) have shown, however, that 21 1 0 1 alloys of this invention successfully pass this test, while ,000 97,500 Previously known gamma Prime shehgthehed cqmmercial The excellent creep-rupture properties of the present alloys were not uniformly satisfactory. 1t is believed that invention Which complement the f r t d stressful)- iron contents over about F these alloys ture properties, are shown in Table V and the fabricability Pressed the degree of hot tensile elongation in the alloys, and welding properties of the invention are shown in thereby resulting in Weld cracking- The following data in Tables VI, VII and VIII. The specimens used in obtain- T l III shows h iron contents above in the alloy ing the data in these tables were 0.063 inch sheet predetrimentally affects the room temperature elongation 3 pared as above-noted and were annealed at 2050" F. for characteristics of the alloy. All specimens tested were 30 minutes and water quenched but not aged.

TABLE V.-C REEF RUPTURE RESULTS FOR ALLOYS OF THIS INVENTION Test Temp- Stress, Life, Elonga- TimeforDelormationol, Hours Alloy No. ature, F. P.s.i. Hours tion,

Percent 0.5% 1.0% 2.0% 5.0%

1n the form of 0.063 inch sheet material annealed and TABLE TEST RESULTS FOR THE ALLOY 0F aged 16 hours at 1400 F. THIS INVENTION TABLE III 50 Alloy Bend Bend Angle, Remarks Radius degrees Alloy Iron Contentjn Weight Tensile, Elongation,

Percent Percent 82 IT 180 No sign of rupture.

83 IT 180 Do. 5. 45 15. 4 84 1T 180 Do. 5. 45 15.3 85 1'1- 180 D0. 3.60 24.2

' TABLE VII.-oLsEN CUP TEST RESULTS FOR THE ALLOY The engineering test data of the as cast weldments OF THIS INVENTION of the alloy of this invention clearly show that the alloy Alloy Thickness Annealed Cl p Depth Maximum has excellent characteristics when produced in the form (Inches) Haldness (mches) mad (lbs') of castings. Moreover, several alloys of this invention, 82 1 R1095 21.050 of the compositions noted in Table II, were made in the 2 82 g}; 3% 5133 1 3538 form of castings. Each had good castability and yielded 2 0637 Rb 95 486 18,625 sound castings without any indication of hot-tearing 8 3223 a? 13233 which is commonly present in gammaprirne alloys of 8 0592 R1180 582 .7 0 8 0592 Rb 79 559 16,250

this class. v

In addition to the foregoing, the graph of FIGURE 1 shows the superiority, as regards stress rupture proper- TABLE Vm HARDNESS OF WELD TEST S M PEG ENS illelzygfohglfggsnigttsigjventlon as compared to commercial FROM THE ALLOY OF THIS INVENTION Table IV further illustrates the industrial importance Amy 23 35; gf if gg ggg 313531 53,";

of the present invention by showing average tensile properties for the previously noted preferred alloy of the 25,51 fig 3213?; 1% 83:32 present mventlon. The samples tested were in the form e 7 Re 28-32 Re 33-36 Rb -86 Rb 81-82 Rb 78-79 of 0.063 inch sheet and were prepared by vacuum induc- The bend tests of Table VI were performed using specimens 6 2; W strips from 0.063" hot rolled sheet and the results show that the alloys of the present invention were capable of being bent 180 around a radius equal to the thickness of the specimen. There was no sign of rupture in the specimen after the test. The results of the standard Olsen Cup test shown in Table VII illustrate the ability of the alloy of the present invention to be easily and successfully shaped and formed into useful articles.

The weld tests of Table VIII involved clamping two specimens in a copper jig positioned for butt welding and Heliarc welding using 9-95 amperes at 12-14 volts with 30 c.f.h. argon cover gas and filler wire formed of the base alloy. These tests show that alloy of the present invention is highly suitable for welded articles.

The following schedule describes an efiective heat treatment for the alloy of the present invention and except where otherwise stated all data set forth in the specification were obtained from specimens that were treated according to the schedule:

I. Anneal for 30 minutes at 205 F. II. Water quench III. Age 16 hours at 1400 F.

IV. Air cool What is claimed is: 1. A nickel base alloy consisting essentially of by weight about Percent Chromium 14 to 17 Tungsten 1 to 3 Iron up to 4.5 Carbon 0.03 to 0.13

2. An alloy in accordance with claim 1 having the following composition:

Percent Chromium 15.5 Tungsten 2 Iron up to 3.5 Carbon 0.08

Vanadium 0.9 Boron 0.007 Molybdenum 7 Aluminum 2 Titanium 3 Silicon up to 0.05 Cobalt less than 1 Nickel balance References Cited UNITED STATES PATENTS 3,061,426 10/1962 Bieber 171 3,183,084 5/1965 Heydt et a1. 75171 3,343,950 9/1967 Richards et al. 75171 3,368,888 2/1968 Winter 75-171 RICHARD O. DEAN, Primary Examiner. 

1. A NICKEL BASE ALLOY CONSISTING ESSENTIALLY OF BY WEIGHT ABOUT 